The long-term objective of our project is to design, build, and market an ophthalmic instrument that simultaneously measures corneal topography and optical aberrations of the human eye using wavefront sensing technology. From these measurements our instrument will provide a complete description of the refractive properties of the anterior cornea, the whole eye, and (by inference the crystalline lens. This optical description will include not only the routine refractive errors of defocus and astigmatism normally measured by present-day optometers and corneal topographers, but will also determine the irregular, higher-order optical aberrations which characterize optically abnormal eyes. Feasibility of the aberrometer component of this dual instrument was proven in a previous STTR grant. The purpose of this Phase-I proposal is to demonstrate feasibility of the corneal topography component by building and testing a prototype instrument using core technology developed with previous STTR support. The major technological advantages of using wavefront sensing technology for corneal topography include: (1) improved performance compared to Placido disk technology, (2) novel assessment of the optical aberrations of the crystalline lens, (3) novel assessment of tear film and keratoconic irregularities, (4) space- and cost-effectiveness derived from application of a single core technology to replace multiple instruments. A combined topographer! aberrometer will help provide wavefront-guided prescriptions for aberration corrections based on inter-ocular lenses, corneal photo-ablative surgery, or contact lenses. The long-term benefits will be improved patient care through improved diagnosis and treatment of optical defects of eyes. PROPOSED COMMERCIAL APPLICATION: Acorneal topographer is a clinical instrument used to map the surface geometry of the cornea of a human eye. Our design of a corneal topographer is based on wavefront sensing technology which has numerous advantages: lower cost, better accuracy, and integrated design with ophthalmic aberrometers. The same basic design concept could also be used to measure surfaces of lenses and mirrors in the optics industry.